The present invention relates generally to medical imaging devices and more particularly to protective covers for providing infection control barriers for such devices.
Each time a medical instrument or device comes in direct contact with a patient there is a danger of cross-contamination between patients, from patients to medical personnel, or vice versa. Therefore, medical devices and instruments that come in direct contact with patients are thoroughly cleaned between uses. For many large, expensive, or complicated medical devices, which are difficult or impossible to clean using conventional methods, cross-contamination prevention is provided by the use of a protective cover placed over the device or over a portion of the device which will come in direct contact with a patient. A clean protective cover is placed on the medical device before each use. Although such protective covers may be cleaned and re-used, typically such protective covers are intended for only a single use and are disposable. Disposable protective covers for medical instruments or devices are typically made of a flexible or semi-rigid plastic material which is generally shaped to fit over the medical instrument or device with which the cover is designed to be used. Examples of medical devices for which such disposable protective covers are regularly employed include laryngoscopes, endoscopes, ultrasound probes, and transesophageal echocardiographic probes. One such device is shown in U.S. Pat. No. 5,363,838. Examples of disposable covers for medical devices are shown in U.S. Pat. Nos. 4,757,381, 5,168,863, 5,201,908, 5,359,991, 5,363,843, 5,406,939, and 5,743,849.
In recent years, advancements in video imaging technology have enabled the development of video imaging medical devices and video imaging accessories for existing medical devices. Examples of such medical imaging devices include dental cameras, retinal cameras, laryngoscope cameras, endoscopes (ENT and upper/lower gastrointestinal), as well as camera systems used for various other types of non-invasive endoscopic surgery. Although the designs of these various medical imaging devices can vary greatly, all such medical imaging devices share some basic design similarities. Generally, a medical imaging device will include a probe portion which is placed within or in contact with a patient. An optical system is placed at the distal end of the probe portion. This optical system may include a miniaturized video camera or simply a lens which is connected to a camera via an optical, e.g., fiber optic, cable running from the distal end of the probe to the proximal end thereof. A light source may also be provided at the distal end of the probe via, e.g., a fiber optic cable running through the probe from the proximal end thereof. The proximal end of the medical imaging device probe is connected to a mechanical structure, e.g., a handle, for positioning the probe. Electrical or optical signals from the optical system mounted in the distal end of the probe are provided via an electrical or optical cable to a computer based imaging and/or analysis system. The electrical or optical signals are converted into a video image, which may be displayed to a user of the device, and other observers, on a system monitor or display. The video image may also be digitized and operated upon by the computer imaging/analysis system for image enhancement and detailed computer analysis of the image.
Since medical imaging devices, and particularly the probe portions thereof, come in direct contact with patients and their bodily fluids, measures must be taken to prevent cross-contamination when such imaging devices are used. Typically, the cost, complexity, and design of most medical imaging devices prevents them from being thoroughly cleaned in a conventional manner between each use. Therefore, protective infection control covers are typically used with such medical imaging devices. Such protective covers typically cover at least the probe portion of the medical imaging device, and may extend to cover other portions of the device as well.
Since medical imaging devices depend on good optical performance for their operation, it is important that any protective cover mounted over the distal end of the imaging device probe be integrated into the optical system mounted therein to assure good image quality and repeatable accurate results. Integration of a protective cover into the optical system used in the medical imaging device requires that the protective cover have a shape and be made of a material which does not interfere with the performance of the medical imaging device. Even a properly designed protective cover can adversely affect system performance if the protective cover is not properly mounted on the imaging device. A protective cover which does not meet the exacting optical specifications (shape and material) for a particular medical imaging device, or is not properly mounted on the device, may lead to a poor visual image, or, in the case of a diagnostic device, an inaccurate result.
Optical pattern detection and identification techniques are widely used in various commercial areas. Such techniques are employed, for example, in bar code systems used for product identification. A UPC bar code is placed on a product. A laser-based bar code reading device is used to detect and identify the bar code and, therefore, the product. A similar identification technique is used for mail sorting, by identifying coded strips on the front of envelopes.
Optical pattern detection and identification techniques are also employed by devices which use video images to measure the dimensions of physical objects, such as molded plastic or machined metal parts. Such video inspection systems are commonly used in metrology laboratories, and are built by a number of companies, including Mitutoyo, Brown and Sharpe, RAM Optical Systems, and others. Objects placed upon the working areas of such systems are viewed with surface illumination, or with background (shadowgraph) illumination to show edge detail.
Optical pattern identification techniques are also used for reading printed pages of material. More complex pattern identification systems exist for recognizing hand-written signatures, retinal patterns, and finger prints.
Known methods for identifying geometric patterns, including text characters, involve first digitizing an image which contains the characters or pattern to be identified. The digitized image is provided to a computer system running a pattern recognition program. Relatively simple pattern recognition programs are used for recognizing basic patterns, including text and simple geometric shapes (lines, circles, squares, etc.), within the digitized image. More complex patterns are recognizable through more complex techniques, such as statistical, structural, or syntactic methods. Even more complex patterns can be recognized through the use of neural networks which can be trained to evaluate patterns and interpolate from them. Examples of optical pattern recognition systems and methods are shown in U.S. Pat. Nos. 4,603,976, 4,809,342, and 5,627,895.
The present invention provides an automated system and method for determining whether a protective cover meeting required specifications is properly mounted on a medical imaging device. The system and method of the present invention employs the optical and imaging/analysis systems of the medical imaging device itself to determine if a protective cover meeting required specifications is in place on the device, and that the protective cover is properly positioned on the device. Visual indicia are placed on a head of the protective cover in the field of view of the medical imaging device optical system. These indicia are included in the video image formed by the optical system. The video image is digitized and analyzed by the medical imaging device imaging/analysis system using pattern recognition algorithms to detect and identify the indicia. The visual indicia may provide information on the nature of the protective cover, e.g., its size, shape, composition, etc., and may be used as alignment marks for the cover. In accordance with the present invention, the medical imaging device is disabled, or a warning signal is provided, if analysis of the indicia in the video image, or lack thereof, indicates that either a protective cover is not present, an incorrect protective cover is being used, or the protective cover is not properly positioned on the device.
The present invention may be employed to provide for the automatic identification of protective covers for medical, dental or veterinary imaging devices. In such imaging devices a video image is created by a video system having an optical system mounted in the distal end of a probe which is placed within or in contact with a patient to be examined. The video image is digitized and provided to a computer based imaging/analysis system. The computer based imaging/analysis system runs imaging and analysis programs for enhancing, displaying, manipulating, and analyzing the video image data.
In order to prevent cross-contamination, a protective cover is placed over the probe of the imaging device to provide an infection control barrier. The protective cover includes a plastic sheath formed to enclose at least a portion of the probe. A transparent head is secured to the plastic sheath. In accordance with the present invention, a protective cover for a medical imaging device includes visual elements or indicia formed on the head of the cover. The visual indicia are formed on the protective cover in an area of the head thereof which lies in the field of view of the imaging device optical system when the cover is properly positioned on the imaging device probe. The protective cover may be manufactured from any suitable optically transparent material, such as glass or plastics, and may be formed by machining, stamping, thermoforming, casting, molding, or any other process. The visual indicia may be formed as part of the head of the cover through the initial forming process, may be created from a different material added during the forming process, or may be applied after the forming process through printing, etching, plating, painting, or some other process. The visual indicia may be in the form of basic geometric shapes (one or more circles, lines, points, polygons, etc.) or more complex outline shapes, may include one or more characters of text, including letters and numbers and/or may include a series of geometric or text elements presented with specific dimensional intervals. The indicia may be conventional machine readable characters such as bar codes. In any case, the indicia will preferably identify the protective cover by size, type, material, etc. The indicia may also be used as alignment markings and/or to provide system calibration data.
Since the indicia are provided on the protective cover in the field of view of the medical imaging device optical system, the digitized video image provided to the device imaging/analysis system will include the indicia if the cover is properly mounted on the device over the device probe. In accordance with the present invention, the digitized video image is processed by pattern recognition algorithms in programs running on the imaging/analysis system computer to detect and identify indicia appearing in the video image. Edge-detection algorithms may be used to detect the perimeters of indicia based on xe2x80x9cbrightnessxe2x80x9d and xe2x80x9cdarknessxe2x80x9d data contained in the video image signal. Contrast enhancement algorithms may be run against the digital image data to enable improved edge detection. The perimeter data is analyzed by pattern recognition algorithms to recognize specific features of the indicia, including lines, curves, or polygons. Recognized indicia patterns are compared with stored indicia patterns to ascertain whether the detected indicia are a valid match for the stored patterns.
If the indicia pattern recognized in the video image does not match any stored valid indicia pattern, the protective cover identification system of the present invention will provide a warning to a user of the imaging device that an incorrect protective cover has been placed on the device. Alternatively, the identification system of the present invention will disable operation of the imaging device unless a valid indicia pattern is recognized. The identification system of the present invention may also provide a warning to a user of the imaging device if the correct indicia pattern does not appear in the proper location on the video image, thereby indicating that the protective cover is not properly positioned on the imaging device. The recognized indicia may also be employed by the imaging device imaging/analysis system for other purposes, such as setting focal distances, calibrating size or distance measurements, or zeroing contrast and brightness settings, depending upon the data provided by the indicia.
The protective cover identification system and method of the present invention may be used in combination with any medical, dental, or veterinary imaging or diagnostic device. The present invention provides an automated system and method for assuring that a protective cover is in place on the imaging or diagnostic device, that the correct protective cover is being used, and that the protective cover is positioned and oriented correctly. Thus, the present invention provides an automated system and method for both ensuring that an infection control barrier is in place and for ensuring that the barrier that is used does not adversely affect operation of the imaging device with which it is employed.
Further objects, features, and advantages of the present invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.